A generic air-conditioning system conducts air to a vehicle interior compartment for the purposes of air-conditioning. For this purpose, the air-conditioning system commonly has a channel system which is flowed through by air during the operation of the air-conditioning system. During the operation of the air-conditioning system, it is desirable to identify properties of the air in the channel system and/or in the vehicle interior compartment and/or outside the air-conditioning system or the associated vehicle, in order to operate the air-conditioning system correspondingly. For example, if the quality of the air in the vehicle interior compartment is better than the quality of the air outside the air-conditioning system or the vehicle, that is to say in the surroundings from which the air-conditioning system draws air, it may be expedient for the air-conditioning system to be operated in an air recirculation mode in which air from the vehicle interior compartment is recirculated.
To determine a property of the air, it is conceivable to use a sensor device. Here, for the detection of the property of the air, use may be made of electromagnetic waves. DE 10 2007 014 519 A1 discloses a sensor device of said type, wherein, within and on an air-conducting channel, there are provided multiple mirrors for the purposes of reflecting light multiple times in order to generate a photoacoustic signal.
The use of a sensor device operated with electromagnetic waves for the purposes of detecting at least one property of air in an air-conditioning system of a vehicle has proven to be difficult in particular owing to the limited available structural spaces and the prerequisites with regard to the admissible weight.